Semiconductor Memory Test Mode Entry in Active State
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Solution Overview
Problem
Synchronous semiconductor memory devices face limitations in test operations, as they can only enter a test mode in the all bank pre-charge mode, restricting the ability to perform tests in various operation modes.
Innovation Solution
A semiconductor memory device with a test mode control block and mode register set control block that enables a test signal in active mode, allowing entry into test mode from both active and all bank pre-charge states, and includes a method for generating and managing test signals to facilitate testing across different operational states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the synchronous semiconductor memory device is restricted to enter test mode only in all bank pre-charge mode, then the test operation can be performed under controlled conditions, but the testing capability is limited and cannot be performed in active mode
Solution Approach 1:
The patent implements dynamic test mode entry capability that adapts to different operational states. The test mode control block dynamically determines whether to enter test mode based on the current bank state, allowing entry from both pre-charge mode (when all banks are in pre-charge) and active mode (when at least one bank is in active state), thereby resolving the contradiction between adaptability and control complexity
Solution Approach 2:
The patent changes the state parameter recognition logic to enable flexible test mode entry. By modifying how the system recognizes and responds to operational state parameters, it allows test mode entry from multiple states (pre-charge and active modes) rather than being restricted to a single state, thus improving adaptability while maintaining manageable complexity
2Productivity
If the test signal is enabled for a predetermined interval in active mode, then testing can be performed in active state improving screening efficiency, but the control logic becomes more complex
Solution Approach 1:
The patent implements preliminary action by pre-configuring the test mode control block with logic to recognize active mode conditions and automatically enable the test signal for the predetermined interval. This preliminary setup allows the system to automatically perform testing during active mode without requiring complex real-time decision logic, thereby improving screening efficiency while keeping control logic manageable
Solution Approach 2:
The patent employs periodic action by enabling the test signal for a predetermined interval during active mode. This time-limited periodic activation allows testing to be performed efficiently during active state without requiring continuous complex control, balancing productivity improvement with acceptable control logic complexity
Data Source
AI summary
A semiconductor memory device is capable of performing a test operation in its various operation modes. Particularly, the semiconductor memory device can enter a test mode in other modes, as well as, an all bank pre-charge mode. The semiconductor memory device includes a test mode control block configured to generate a test signal enabled for a predetermined interval in an active mode, and a mode register set control block configured to enable a mode register set signal for a test operation in the predetermined interval in response to the test signal.